Bellows shaft seal protector



April 1949- R. DLSNYDER 2,467,239

BELLOWS SHAFT SEAL PROTECTOR Filed July 30, 1945 INVENTOR. v

Patented Apr. 12, 1949 BELLOWS SHAFT SEAL PROTECTOR Russel D. Snyder, Chicago, Ill., assignor to Crane Packing Company, Chicago, L, a corporation of Illinois Application July 30, 1945, Serial No. 607,821

- 3 Claims. 1

This invention relates to scaling devices and particularly to that class of sealing devices which utilizesa pair of relatively rotatable radially disposed surfaces for eifecting a fluid-tight connection between the relatively rotatable parts.

The principal object of this invention is to provide an improvement upon the seal disclosed in my prior Patent No. 2,360,372, which improvement will adapt the aforesaid sealing device for a greater variety of uses. More specifically, the principal object of this invention is to provide a means for protecting the resilient bellows sealing element of the device from damage due to the application of high pressure internally of the bellows such that a fold thereof would be forced into the pin and slot driving connection for one of the sealing elements.

A more specific object of this invention is to provide a ferrule between the apex of the fold of a bellows seal and a lug-and-slot connection adjacent the fold such that the ferrule will protect the apex from entering the lug-and-slot connection.

These and other objects and features of this invention will become apparent from the followingdescription when, taken together with the accompanying drawings, in which Fig. 1 is a fragmentary side elevation in section of a seal incorporating the protective device of this invention;

Fig. 2 is the same view showing the seal extended so that the slot is exposed and with the protective ferrule shown over the exposed slots; and

Fig. 3 is an end view of the lug-and-slot connection taken along line 3-3 of Fig. 2.

Referring in detail now to the drawings and particularly to Fig. 1, there is shown a rotatable element in which may be the shaft of a compressor or other fluid working device. and a housing ll spaced from shaft l so as to form a chamber l2 therebetween, said chamber being normally at a much lower pressure than the exterior of the housing. Chamber i2 is defined in part by a closure member I3 which is secured by means of bolts M or other fasteners to housing ii, the exterior of chamber I2 so formed being in communication with fluid under pressure. Thus chamber |2 may be at sub-atmospheric pressure and the exterior at atmospheric pressure, or housing l2 may be immersed in a fluid having a considerable static or pressure head. On the inside of closure member l3 there is formed a laterally extending ring l5 having a surface I6 disposed normally to the axis of rotation of shaft l0 and which constitutes one of the sealing surfaces of the device. Adjacent ring I6 is a sealing washer l1 having a similar ring l8 on which is formed a sealing surface l9, said surface l8 being maintained in engagement with sealing surface l6 so as to form a fluid-tight seal therebetween.

A seal is formed between washer I1 and shaft H! by means of a flexible deformable sleeve 20 preferably made of rubber, either natural or synthetic, or a combination of the two, and formed with spaced flanges 2| and 22 connected by a fold 36, flange 2| being preloaded upon shaft III by means of a rigid band 23, and flange 22 being held against the left-hand surface (Fig. l) or back of washer H. The holding means for flange 22 comprises. a washer. 24 made of rigid material such as brass, steel or the like, a shell 25 surrounding flange 22, and washers I1 and 24; and a spring 26 which is compressed between a spring retainer 21 and a flange 28 formed on the end of sleeve 25. Spring retainer 21 abuts a shoulder 29 or other raised surface formed on shaft ill and hence is held against axial movement to the left under the action of spring 26. Shell 25 has a portion of reduced diameter 30 which forms a shoulder 3| by means of which this spring pressure is transmitted directly to washer 24.

One or more small depressions 32 are formed in the outer periphery of shell 25, said depressions fitting into corresponding slots 33 formed in washer H to provide a driving connection between the sleeve and washer. Band 23 is formed with radially extending lugs 34 which fit into slots 35 formed in the end of reduced section 30 of shell 25. Lugs 34 (Fig. 3) are relatively wide circumferentially so that the slots 35 are likewise correspondingly wide. Thus, when shell 25 is moved to the right in Fig. 1 under the action of spring 26, a considerable opening, or rather series of openings, ispresented to the sealing sleeve 20. The fold 36 of sleeve 20 is so shaped that the apex of the fold is found in the vicinity of the slot 35.

Referring now to Fig. 2, it will be seen that fold 36 when subject to internal pressure would be forced into the slots 35 and if sufiicient pressure is provided and likewise a sufiicient axial movement of shell' 25 occurs, the fold will be forced into the slot and may eventually rupture, thereby destroying the seal.

To alleviate this situation, in accordance with the present invention, a ferrule 31 is inserted between the apex of fold 36 and the inside of shell 25. This ferrule is formed with a cylindrical section 38 which is of sufficient axial extent to completely cover slots 35 when the-seal is in its most extended position, and with a short radially inwardly extending section 33 which bears against the lugs on one side and against the fold 36 on the other, so that said ferrule 31 is constrained to remain in substantially the position inwhich it is shown in Figs. 1 and 2. This is f particularly true when the inside of the bellowsis subjected to pressure and thereby presents a considerable resistance to such deformation as would be necessary to cause inwardly extending flange 39 to pass over the apex 36 of the fold.

Ferrule 31 is preferably made of rigid material such as metal and is freely slidable on the inside of reduced portion 30 of shell 35. Attention is directed to the fact that the inside diameter of flange 39 of ferrule 31 is at least as great asthe external diameter of band 23. It is also pointed out that lugs 34 extend radially outwardly from the outer surface of band 23 so that the .;contact 7 between flange 39 and the right-hand edge (Figs. 1 and 2) of band 23, is a solid line contact and may be a continuous surface contact despite the fact that lugs 34 are discontinuous. V

A ferrule 40 is provided between the forward part of sleeve and shaft Ill to prevent this part of the sleeve from contacting the shaft and possibly freezing thereto.

It will be observed that the greatest internaldiameter of fold 36 is greater than the internal diameter of ring l8 of washer ll so that with fluid under pressure on the inside of fold 38 there will be a net effective area of pressure in the direction of sealing surface l6 onclosure member l3, so as to assist in maintaining these surfaces in contact with one another. Similarly, it will be noted that the diameter of the bellows adjacent ring 22 is less than the outside diameter of ring It so that should pressure be-applied to the outside of the seal, there will be a net effective pressure in the direction of sealing surface l6 tending to help maintain this surface and sealing surface IS in fluid-tight contact. Thus the seal illustrated in Figs. land 2 is adapted for use with either internal or external pressure and, when the pressure is applied internally, there is no danger of the bellows blowing out through the slots since ferrule 3! completely conceals the slots at any working position of washer I7 relative to ring 2| which is preloaded on shaft Ill. These extreme positions are illustrated in Figs. 1 and 2, Fig. 1 showing ring l8 as it would appear when first installed, and Fig. 2 showing ring l8 as it would appear after it had been almost completely worn.

- It is understood that the foregoing description is merely illustrative of a preferred embodiment ofthis invention and that the scope of the invention therefore is not to be limited thereto but it is to be determined by the appended claims.

What is claimed is:

1. In a sealing unit for effecting a fluid seal between two relatively rotatable structures, a sealing washer. a shell concentric with the washer for driving the washer, a sealing element for effecting a seal between the washer and one of the structures, said element having a flexible fold within the'shell, a band rotatable with the said one of the structures, said shell having slots in proximity to the fold, lugs on the band extending into the slots and being movable therein axially of the shell, and means interposed between the fold and shell and movable with the lugs relative to the shell to cover the slots, whereby to prevent the fold from entering the slots when subjected to pressure inthe direction of the slots. V

2. In a sealing unit for effecting a fluid seal between two relatively rotatable structures, a sealing washer, a shell concentric with the washer and having a driving connection therewith, a sealing element for effecting a seal between the washer and the said one of the structures, said element having a flexible fold within the shell, a band rotatable with the said one of the structures, said shell having slots in proximity' to 'the fold, lugson the band extending into tending flange adjacent the lugs.

RUSSEL DJSN'YDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

